1. Field of the Invention
The present invention relates to a method of measuring insulation resistance of a capacitor and an insulation resistance measuring apparatus of the capacitor for measuring an insulation resistance of the capacitor.
2. Related Background Art
In order to compare whether or not an insulation resistance of a capacitor is not normal, there is known a technique which applies a predetermined DC voltage to a capacitor at a state of connecting a current-limiting resistor and measures the insulation resistance of the capacitor based on a leak current of the capacitor measured after a predetermined time.
A conventional insulation resistance measurement system prescribed by JIS C 5102 has been employed and used in measuring the insulation resistance of a work such as the capacitor. In this system, a predetermined measured voltage is applied to the work, and a current flowing through the work is measured after 60xc2x15 seconds.
At present, there is a demand for mass production and high quality in electronic components such as the capacitor, and the demand cannot be satisfied in the conventional technique of measuring the insulation resistance over a time of about 60 seconds per one capacitor.
There has been proposed a work test method for testing and classifying the works by intermittently applying the DC voltage to the works (Japanese Patent No. 2578440). This method is suitable for measuring or testing property of the works contained in a work-pocket disposed at a constant interval along an outer periphery of a turntable, while the turntable is intermittently rotated. More specifically, after the DC voltage is intermittently applied to the work twice, the property of the work is measured and tested, and then the work is discharged.
However, it is difficult to measure the insulation resistance of the work by the method disclosed in the publication. The reason is that a conventional technology has employed a so-called resistance charging method in which the DC voltage is continuously applied to the capacitor at a state of connecting the current-limiting resistor to the capacitor. Therefore, a certain time constant is required for reaching the applied voltage, and a value of the insulation resistance is uncertain particularly at an initial state of applying the voltage.
Moreover, as an insulation resistance measurement method using the turntable, there is proposed a method of measuring/testing the insulation resistance of the capacitor one by one via a plurality of charging portions connected to the current-limiting resistance, at a state of applying the measuring voltage to the capacitor for a predetermined time. However, since the measuring voltage has to be applied to the work for a long time, the method is not suitable for the test in mass production.
The present invention has been developed in consideration of this respect, and an object thereof is to provide a method of measuring insulation resistance of the capacitor and an insulation resistance measuring apparatus of the capacitor, in which an insulation resistance of the capacitor can easily, quickly and precisely be measured.
According to the present invention, there is provided a method of measuring an insulation resistance of an capacitor, comprising:
a step of intermittently applying a constant voltage to the capacitor, and intermittently measuring a current flowing through said capacitor; and
a step of intermittently detecting a value of the insulation resistance of said capacitor based on values of the measured current and the applied constant voltage.
Furthermore, there is provided an insulation resistance measuring apparatus, comprising:
a power source for intermittently applying a constant voltage to a capacitor;
current measuring means for intermittently measuring a current flowing through said capacitor while applying the constant voltage to said capacitor;
resistance measuring means for intermittently detecting an insulation resistance of said capacitor based on the measured current value and the constant voltage value; and
comparing means for comparing defective/non-defective of said capacitor based on the insulation resistance detected by said resistance measuring means.